LEDs are a solid state lamps that use semiconductor material instead of a filament or neon gas. When compared to traditional (i.e., fluorescent or incandescent) light bulbs, LEDs offer a number of advantages. For example, because LEDs operate on low voltage and consume less power, they are less expensive to operate and generate significantly less heat than traditional light bulbs. Also, because LEDs are of solid state design, they are more durable and less likely to break than traditional bulbs. Another advantage of LEDs is their long life. Some LED lamps can operate for up to 100,000 hours, compared to about 1500 hours for a standard filament light bulb. Moreover, LEDs are environmentally friendly, contain no mercury and produce no electromagnetic emissions. Another advantage is that a single LED bulb can produce many different colors without the need for colored coatings or lenses.
The prior art has included a number of LED lighting modules. For example, U.S. Pat. No. 7,175,306 (Pan) describes an LED illuminating module includes a supporting frame and an illuminating unit. The supporting frame has a top surface and an elongated reflective channel indented on the top surface and defining a peripheral reflective wall inclinedly extended from a bottom wall of the reflective channel. The illumination unit includes a light circuit supported by the supporting frame and a plurality of illuminators which are electrically mounted to the light circuit and spacedly aligned along the reflective channel, wherein each of the illuminators forms as a point of light source for radially emitting light towards the reflective wall, such that the reflective wall is adapted for reflectively accumulating the lights of the illuminators within the reflective channel, so as to merge the points of light source to form a line of light source along the reflective channel.
U.S. Pat. No. 7,125,143 (Hacker) describes an LED module having a plurality of mixed-light LEDs and additional LEDs, wherein each of the additional LEDs has a plurality of LED chips. The LED chips have different emission wavelengths, which, in each instance, are arranged in a common housing.
U.S. Pat. No. 7,045,965 (Li et al.) describes a lighting module that includes a pair of LEDs having the same polarity connected in parallel. These parallel LEDs with the same polarity are purported to increase the reliability of the light module and make it suitable for use in light strings where a relatively large number of such light modules are connected in series and where the failure of one such light module will cause the failure of the entire light string.
One area where LED lighting modules are now used is in the lighting of channel letter signage. Channel letter sinage typically consists of a series of Iluminated channel letters, each of which consists of a channel (e.g., generally “U” shapped) housing in the form of a letter, one or more light emitters mounted within the channel housing and a translucent lens positioned over the front of the housing to transmit light from within the housing. Channel letters are commonly found on the outside of buildings and are often used to advertise the name of the business. Channel letters have typically been illuminated by neon or fluorescent light sources that are mounted within the channel housing. However, such neon and fluorescent light sources have a relatively short operating lives, are fragile, require high voltage (e.g., 7,000 to 15,000 volts for neon) and can be expensive to operate because they consume substantial amounts of power.
U.S. Pat. No. 6,923,495 (Sloan et al.) describes the use of LEDs for channel letter lighting and, in particular, a channel letter lighting unit that comprises a printed circuit board (PCB) having a linear row of light emitting elements, such as LEDs. Input wires transmit a power signal to the PCB to illuminate the plurality of light emitting elements, and output wires transmit the power signal from the PCB. The PCB is mounted within an elongate, thermally conductive extrusion such that light emitted from the row of LEDs transmits light away from the extrusion. The extrusion purportedly promotes the dissipation of heat from the LEDs. A mounting mechanism is included for mounting the extrusion within a channel letter housing. A plurality of these channel lighting units may be electrically connected to one another so that a power signal applied to the lighting system is transmitted to each of the plurality of lighting units.
There remains a need in the art for the development of improved LED lighting modules that may be useable in channel letter lighting applications and/or other applications.